The present invention relates to a hospital bed. More particularly, the present invention relates to an improved mechanism for raising and lowering a hospital bed.
Hospital beds must typically have the ability to raise and descend in order to make it easier for patients to get into and out of the hospital bed. It is desirable for the bed to be able to be lowered as close to the ground as possible. In addition, it is desirable to provide adequate space beneath a patient support surface of the bed to permit medical equipment to move underneath the support surface during various medical procedures.
It is also important for the hospital bed to have the capability of shifting to a Trendelenburg position in which the patient support surface is inclined with a head end of the patient support surface lowered below a foot end. The Trendelenburg position is important for the patient's well being if the patient should undergo cardiac arrest.
The novel lifting apparatus of the present invention advantageously provides these important features while reducing the overall weight of the bed. In addition, the present invention minimizes surface deflection or "spring board effect" of the sleep surface of the bed. The present invention also advantageously provides complete access for fluoroscopic equipment such as C-Arm units from the patient's subclavian area through the patient's femoral area. The lifting apparatus of the present invention also provides a mechanical apparatus for achieving automatic Trendelenburg and reverse Trendelenburg positions.
According to one aspect of the present invention, a hospital bed includes a base and a deck for supporting a patient support surface. The bed also includes a scissors lift linkage coupled between the base and the deck. The scissors lift linkage is movable from an extended position to a retracted position to raise and lower, respectively, the deck relative to the base. The bed further includes a controller for selectively moving the scissors lift linkage between its extended position and its retracted position.
According to another aspect of the present invention, a hospital bed includes a base and a deck having a head end and a foot end. The bed also includes a first scissors lift linkage coupled between the base and the deck adjacent the head end of the deck. The first scissors lift linkage is movable from an extended position to a retracted position to raise and lower, respectively, the head end of the deck relative to the base. The bed further includes a second scissors lift linkage coupled between the base and the deck adjacent the foot end of the deck. The second scissors lift linkage is movable from an extended position to a retracted position to raise and lower, respectively, the foot end of the deck relative to the base. The bed still further includes a controller for selectively and independently moving the first and second scissors lift linkages between the extended positions and the retracted positions.
In the illustrated embodiment, the first scissors lift linkage is pivotably coupled to both the base and the deck, and the second scissors lift linkage is rigidly coupled to the base and pivotably coupled to the deck. The second scissors lift linkage is illustratively aligned in a plane which is generally perpendicular to a plane of the first scissors lift linkage to stabilize the deck relative to the base.
Also in the illustrated embodiment, the controller includes a first cylinder having a first piston coupled to the first scissors lift linkage. The first piston is movable from an extended position to a retracted position to move the first scissors lift linkage between its extended position and its retracted position, respectively. The controller also includes a second cylinder having a second piston coupled to the second scissors lift linkage. The second piston is movable from an extended position to a retracted position to move the second scissors lift linkage between its extended position and its retracted position, respectively. The first and second cylinders are illustratively pivotably coupled to the base, and the first and second pistons are pivotably coupled to the first and second scissors lift linkages, respectively.
Also in the illustrated embodiment, the first scissors lift linkage includes a pair of parallel first scissors mechanisms coupled together by top and bottom frame members. First sides of the first scissors mechanisms are pivotably coupled to the top and bottom frame members and second sides of the first scissors mechanisms are slidably coupled to the top and bottom frame members. The second scissors lift linkage includes a pair of parallel second scissors mechanisms coupled together by top and bottom frame members. First sides of both of the second scissors mechanisms are pivotably coupled to the top and bottom frame members, and second sides of the second scissors mechanisms are slidably coupled to the top and bottom frame members.
The controller illustratively includes means for moving the first scissors lift linkage to its retracted position and for moving the second scissors lift linkage to its extended position to align the deck in a Trendelenburg position. The controller also includes means for moving the first scissors lift linkage to its extended position and for moving the second scissors lift linkage to its retracted position to align the deck in a reverse Trendelenburg position.
As discussed above, the first and second scissors lift linkages are mounted generally perpendicular to each other. By mounting the scissors linkages generally perpendicular to each other, the present invention maximizes access under the deck for fluoroscopic equipment such as C-Arms, while minimizing the amount of unsupported length on the deck to reduce sleep surface deflection or spring board effect. Scissors lift linkages are stable in a plane perpendicular to the plane of the scissors lift linkage. Therefore, by providing first and second scissor lift linkages mounted perpendicular to each other, the lifting apparatus of the present invention provides stability for the hospital bed in all directions.
Advantageously, each scissors lift linkage is actuated by one single acting hydraulic or air cylinder. The piston of the cylinders have a stroke length of about 6 inches, while the scissors lift linkages each have a 20 1/4 inch stroke. Therefore, the mechanical advantage of the scissors lift linkages is over three times magnification of the input displacement of the piston of the cylinder. Therefore, the present invention facilitates moving the hospital bed to a low position by permitting use of smaller stroke cylinders. Due to the mechanical advantage of the scissors style lift linkage, the hospital bed of the present invention maximizes the range of movement of the deck from its low position to its elevated position.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.